逆境条件下糯玉米水分利用效率和水通道蛋白表达差异研究

Differences in water use efficiency and aquaporin gene expression in waxy maize varieties under different stress conditions

水肥耦合是作物水分和养分高效利用的重要机制,其中水通道蛋白(AQP)发挥重要作用。本文研究了逆境条件下3个糯玉米品种水分利用效率(WUE)和水通道蛋白(AQP)表达差异及其关系。在低氮(0.5N,其中培养液的氮元素含量减半)、高氮(1.5N,其中培养液的氮元素含量增加1/2)、干旱(10%PEG即-0.1 MPa)和盐(200 mmol.L-1 NaCl)胁迫处理下测定了叶片水分利用效率(WUEL),并采用半定量逆转录聚合酶链式反应(RT-PCR)体系检测3个AQP基因在糯玉米根系中的表达情况。结果表明:(1)0.5N处理下,3个品种的WUEL多低于CK;1.5N和PEG处理下,3个品种的WUEL多高于CK。(2)TIP3.1、TIP2a、TIP2b 3个基因在0.5N处理下表现为不表达或表达下调,1.5N处理下6 h和PEG处理下9 h多表现表达上调,说明TIPs基因家族表达受营养、干旱和盐胁迫诱导。(3)TIPs的上述3个基因的表达和WUEL都在0.5N处理下低于CK,在1.5N和PEG处理下不同程度地高于CK,说明TIPs基因表达与WUEL的变化有密切响应关系。以上结果说明WUE与TIPs基因转录水平的调控有一定关系,且品种间存在较大差异。

Aquaporin（AQP） is critical in coupling water and nutrients,which is an important mechanism of crop water（WUE） and nutrient（NUE） use efficiency.Differences in leaf water use efficiency（LWUE） and in aquaporin gene expression in waxy maize varieties were tested under various stress conditions.The stress conditions used in the study included low nitrogen（0.5N,half dose nitrogen of 0.5 Hoagland solution）,high nitrogen（1.5N,1.5 times nitrogen of 0.5 Hoagland solution）,drought（10% PEG with ？0.1 MPa water potential） and salt（200 mmol·L？1 NaCl）.Expressions of three AQP genes in the roots of waxy maize were tested by the RT-PCR method.The results showed that LWUE in three waxy maize varieties was less under 0.5N treatment than that under CK.It was,however,higher than that of CK under 1.5N and PEG treatments.TIP2a,TIP2b and TIP3.1 genes expressions were partially or completely suppressed under 0.5N stress treatment.The gene expressions were,however,amplified under 1.5N（for 6 h） and PEG（for 9 h） treatments.This suggested that TIP gene family was enhanced by nitrogen,drought and salt stress.Furthermore,the expression of TIP and LWUE were weaker under 0.5N treatment than under CK,but stronger on different degrees under PEG and 1.5N treatments than under CK.Close relations were noted between TIP gene expression and change in WUEL.These findings indicated that WUE was largely controlled by the levels of TIP expression,which was different among waxy maize varieties.